Radar is used for detection and tracking of distant objects. In some cases it is important to know the location of a target with great accuracy, as might be the case when tracking a hostile incoming missile (a “target” in radar parlance). Under such conditions, various factors can adversely affect the radar-indicated location of the target. Among these factors are refraction of radio-frequency (RF) electromagnetic radiation by the atmosphere through which the electromagnetic signals propagate.
Traditional methods of determining atmospheric refraction include the use of a refractive index. This index can be determined based on the radar location and atmospheric conditions, and is usually available in a table. However, atmospheric conditions can change frequently, and up-to-date information may not always be available. Improved, real-time methods for determining atmospheric refraction are desired. Once the refraction is deemed to be known, the radar-indicated location of the target can be corrected for the refraction.
Improved or alternative methods are desired for determining the effects of refraction on a radar RF beam.